Making Sequences is Fun

题意翻译

定义 $S(i)=i$ 的位数，如 $S(893)=3,S(114514)=6$ 数 $x$ 的费用为 $k\times S(i)$ 你有 $w$ 元钱，要从 $m$ 开始连续添加尽量多的数 $(m,m+1,m+2,\cdots)$ 组成一个序列，问这个序列最长有多长。

题目描述

We'll define $ S(n) $ for positive integer $ n $ as follows: the number of the $ n $ 's digits in the decimal base. For example, $ S(893)=3 $ , $ S(114514)=6 $ . You want to make a consecutive integer sequence starting from number $ m $ ( $ m,m+1,... $ ). But you need to pay $ S(n)·k $ to add the number $ n $ to the sequence. You can spend a cost up to $ w $ , and you want to make the sequence as long as possible. Write a program that tells sequence's maximum length.

输入输出格式

输入格式

The first line contains three integers $ w $ ( $ 1<=w<=10^{16} $ ), $ m $ ( $ 1<=m<=10^{16} $ ), $ k $ ( $ 1<=k<=10^{9} $ ). Please, do not write the %lld specifier to read or write 64-bit integers in C++. It is preferred to use the cin, cout streams or the %I64d specifier.

输出格式

The first line should contain a single integer — the answer to the problem.

输入输出样例

输入样例 #1

9 1 1

输出样例 #1

9

输入样例 #2

77 7 7

输出样例 #2

7

输入样例 #3

114 5 14

输出样例 #3

6

输入样例 #4

1 1 2

输出样例 #4

0